Sulfur vaporizing apparatus



Sem- 6 i949@ w. T. GRACE ET AL 2,48,411

SULFUR VAPORIZING APPARATUS Q riginal Filed Deo. 28, 1940 w 2Sheets-Sheet 1 W/ra'nyozz f Grace n Jose/viz CML/Ueli Jr INVENTOR w. T.GRACE ET AL.

SULFUR VAPOR-IZING APPARATUS original Filed Deck. 28, 1945 l Sept0 6,1949.`

2 Sheets-Sheet 2 K a m.

n JM 0 W MC .nk o w, WM, J

Patented Sept. 6, v1949 SULFUR VAPORIZING APPARATUS Worthington T.Grace, Upper Darby, Pa., and

Joseph C. Muller, Jr., Little Falls, N. J., assignors to E. I. du Pontde Nemours & Company, Wilmington, Del., a corporation of DelawareOriginal application December 28, 1940, Serial No. 372,016. Divided andthis application October 25, 1941, Serial No. 416,512. In CanadaSeptember 18, 1941 8 Claims.

This invention relates to the manufacture of sulfur dioxide and isparticularly directed to sulfur burners in which high temperature fluentsulfur is continuously circulated through a volatilization chamberwhereby sulfur is vaporized and residue is continuously swept from thevolatilization zone. This application is a division of our co-pendingapplication, Ser. No. 372,076, led December 28, 1940, now issued asPatent 2,445,112, July 13, 1948.

One of the simplest and least expensive types of brimstone burners usedfor the production of sulfur dioxide gas is the so-called brick or pantype burner. This burner consists essentially of a rectangular bricklined' iron pan over which is a brick combustion chamber. The solidbrimstone is fed into one end of the pan continuously by means of ascrew where it is melted by the heat of the burner. Usually the pan iskept filled with molten sulfur.

This type of burner has two serious defects which interfere with theuniformity of operation. First, the ash and dirt present in thebrimstone gradually accumulate in the pan and periodically the sulfur inthe pan must be burned out and the accumulated ash removed. Thisinterrupts operations for several hours. Attempts to remove the ashcurrently have been made but the results were not satisfactory becausethe agitation of the surface of the molten sulfur by the rakes causesfluctuations in the strength of the sulfur dioxide gas. Second,brimstone contains a small amount of oil or organic matter which formsan asphaltic-like material in the burner. This material floats on thesurface of the molten :sulfur1 prevents volatilization of sulfur, andreduces the area of burning surface. Any disturbance of this blanket onthe surface of the molten sulfur results in a sudden increase in thestrength ofV sulfur dioxide gas. Both the ash and the floating materialinterfere seriously with the maintenance of a uniform quantity ofuniform strength sulfur dioxide gas so essential to good operation ofcontinuous sulfuric acid processes.

We have now found that these disadvantages can be avoided by means ofapparatus made in accordance with the invention as more particularlyhereinafter described.

Suitable apparatus according to the invention are illustrated in theaccompanying drawing in which Figure 1 is a side elevation in section;Figure 2 is a plan view in section taken along lines 2 2, Figure 1;.Figure 3 is a front elevation in section along lines 3-3, Figure 4;Figure 4 is a plan .View of Figure 2; Figure 5 is a plan view showing amodified form of the hearth illustrated in Figure 2; and Figures 6 and 7are plan views showing further modifications of the hearth shown inFigure 2.

The sulfur burner, as illustrated in Figure 1, is generally similar tothe usual pan type burners and consists generally of a volatilizationchamber I and a combustion chamber 2 defined in the brick housing 3 bythe arch partition 4.

The bottom of the burner, which is supported on any suitable supportingstructure 5, is arranged as an inclined plane sloping from the rear ofthe burner to the front at a suitable slope, say about 1 to 12. Thisarrangement provides a sloping hearth 6 down which molten sulfur isadapted to flow in a shallow stream so as to prevent accumulations ofresidue on the hearth. The hearth is provided with side walls 1 which,as illustrated in Figure 2, are arranged so that the sloping hearth 6has a progressively decreasing width to prevent any pockets in whichdirt and ash could accumulate.

The front wall 8 of the furnace is provided with a centrally locatedopening 9 which serves as an air port and also as an exit port for thehigh temperature fluent sulfur. The latter flows from the hearth 6 thruthe conduit IIJ into the settling pit II Where the ash and dirt settleout. The supernatant sulfur is pumped from the pit by the pump I2 andpasses thru the pipe I3 to the head of the sloping hearth Where it feedsout onto the hearth at one or more places, as for example from the opennozzle I 4.

Solid, raw sulfur is also fed to the head of the sloping hearth 6 thruthe opening I5 in the rear Wall I6 of the furnace. Any suitable feedmechanism such as a hopper 53, and screw 54 may be used. The rate offeed of solid sulfur is regulated by means of a suitable variable speedfeed mechanism 55 controlled by feed mechanism control 56 which isactuated by the float II in the settling pit II. This makes it possibleautomatically to regulate the solid sulfur feed as required tocompensate for sulfur vaporized in the passage of the high temperaturefluent sulfur down the sloping hearth 6. Automatic control of thischaracter coupled with automatic control of admission of air to one orthe other or both of the primary air port I8 or the secondary air poorI8a by means of a suitable sulfur dioxide analyzer makes the entireoperation automatic and continuous, a result which could not beaccomplished in the conventional type pan burner due to incrustations onthe molten body of sulfur and accumulation of dirt and ash.

The settling pit Il, as more particularly illustrated in Figures 2, 3,and 4, is a generally rectangular pit provided with an inclinedwall I9up which dirt andash may be raked by either manual or mechanical meansinto the clean-out box 22. inwardly about half way up the sloping wallIS, as shown at 23, in order to facilitate the raking by means of ablower in the sulfur dioxide line.

The side walls 2l and 22 of the pit taper..V

out of dirt and ash into the clean-out box 20.

The conduit I feeds into the settling p'it, as shown at 2d, below thelevel of liquid Vsulfur therein, the purpose being to extinguish the Y 1flames on the surface of the flowing sulfur. The

walls and 26 serve as baiiies to direct the mol-.

ten sulfur newly introduced towards the bottoni'L of the pit, to reducethe burning of the sulfur in the pit, and to guide the float. The fioatI1 is located in the compartment defined by partitions 25 and 26, butany other suitable location will Suffice; The pump I2 is located in thecompartn ment defined by partition 26 and the Vend wall 'IV of thesettling pit. Any'suitable pump or` vapor lift may be employed providedthe intake is located well above the bottom of the pit.

The top of the sewing p11; is provided with a -f tight cover 28 so as toexclude air and minimize the amount of burning in the pit..` The coverextends over the entirertop of the settling pit; andis so shaped Vas toprovide a hood 37 which communicates -with the opening 9 in the furnaceand to form part ofthe clean-out box 2,0.

The clean-out box 20. forms an extension around the clean-out end 29.:It is composed ofY atop'wall 3U, a bottom 3|, a front wall 32, and

two side walls ,33 and 34..-l The other wall is provided by the inclinedwall I9 of the settling4 pit. The upper corner `of vthe clean-out box2li` is cut away and provided with a removable closure 35. The cut-outis so located that-when the cover is'removed theopening in the cleanfout box is opposite the clean-out end 2 9 so thatv a rake or hoe may beintroduced into the cleaning pit for theiremoval of dirt and'ash whichhas settled to the bottom. Asthis dirt and ash is raked out intov theclean-out box 20 it contains appreciable amounts of sulfur. This is`burned, in the clean-out box by air admitted thru the ports 36 in theside walls. The sulfur, vapors yand sulfur dioxide thus formedValongkwith the sulfur vapor and sulfur dioxide which emanate fromthepit pass up under thehood 3l and thru the opening 9 into the burner.VThe frontend of-the'hood SIjis fitted with a door 38 whichmay-be removedforinspection of the hearth- E. The door 38 is provided with a small airport f39 so that air is i" drawn in'thru the hood and sweeps the sulfurdioxide andV sulfur vapors passing up from the clean-out box andsettling pit into the burner. In this manner all the sulfurvalue isrecovered. The clean-out box also is providedwith-an opening 40 and thehinged closure 4I inorder that Y the burnedlout residue maybe removed.

.In operation the settling pit ,provides` a veryV efficient way ofseparating limpurities* fromvthe high temperature fluent sulfur.V Twofactors contribute to this result. In the rst place, the settling pitoperates on high temperature fluent sulfur whereas in the prior artuseof settling pits the sulfur has uniformly been low temperature fluentsulfurf In. the second place, in its passage P thru the vaporizationzone the'rhigh temperature fluent y sulfur becomes relativelyAconcentrated with respect to theimpurities in the degree that thesulfur is vaporized and the impurities are. not.

In operation of the burner the draft is created into the combustionchamber 2.'

Air therefore is drawn into the burner thru the variousairportslprovided. A.'Iheair, for primary combustion Ais regulated.yby'varying the'gsize of the air port I8. Additional air may be admittedSecondary air is admitted thru a suitable port I8a and, depending 'uponthe location of the port, may act mainly as a diluent or may contributeto the combustion ofthe sulfur vapor.y We find that it is most gen-Verallyrdesirable to manually adjust theeprimary air as required. forsatisfactory'operation of the burner and to automatically adjust thesecondary air as required to maintain a constant sulfur Vdioxide.content inthe sulfur dioxide gas. Automatic sulfur dioxide recordercontrollers are available on the'market and may be made to operate avsuitable damper for the air port I8a according to standard practices inthe art.

In a modied form .of the invention,V asxillustrated in Figure 5, thereis provided a partition 42 which separates the dry sulfurfedto. thehearthyfrom the high temperaturegfiuent sulfur fed to the hearth bythenozzle I4. The purpose of .partition 42 is tto permit the solid sulfurto. Ymelt before it enters the stream of-recirculated sulfur, otherwisesome lumps may be carried thru the burnerbefore they are completelymelted. A similar modication is illustratedin Figure 6 Where partitions43 yand,44;-iso1ate thesdry sulfur feedl from the high temperaturefluent sulfurfeed to the hearththru the nozzles I 4. g, Y

seu a, further modicauonis illustrated in Fig-1 ure?. In thismodification'thehightemperature iiuentl sulfur instead ofi-beingrecirculated tothe. upper end of thehearth is passedv intoa m'eltil'xgvpit 45 providedvwith a. hopper `andescrewieed mechanism 4.,forfeeding.solid sulfur. A The heat content of the high temperaturelfluent sulfuris thus .utilized to melt the'sulfur.A Themelting pit 45communicateswith thehearth 41 thru' the opening 48 in the back wall 49of the burner so' that the overflow ofthemelting pit, which is hightemperature fluent sulfur augmented'by the sulfm which is melted in thepit, passes into thev vaporizing zone.;v The sloping hearth 41 is alsoprovided with converging Walls and 5I which act progressively-todiminish the hearth width as thesulfur flowsdown toward the outlet I52.The

` outlet52 feeds into a settling pit `(not shown) which," if desired,vmay be constructed as illustrated in Figures 2, 3 and 4. l

Inth e modification shownin Figure 7 it is not required that thesettling pit have such large ca-V pacity because a substantialamount ofsedirnenv tation of ash anddirt is. effected in the melting pit 45. kAsVthe outlet 48 of the melting pit 45V is arranged toztake the overflowthe floatingY carbonaceous material will pass into the burner and isVeventually separated in the settlingpit.: By

suitable construction the two pits canbe madeV to divide lthe load ofresidue in any desiredrnan-Y '700 f the viscosity drops vbackv to..about "three poises, and at 800"F. to' about one poise. Thus moltensulfur exists in two fluent states and one viscous state.A We speak ofhigh temperature fluent sulfur with reference to the fluent state nearthe boiling point and in contradistinction to the fluent state near themelting point.

When dry sulfur is fed to the hearth 6 it passes thru the lowtemperature fluent state, the viscous state and the'high temperaturefluent state. In the modification shown in Figures 1 and 2 lowtemperature fluent sulfur flows away from a pile of dry sulfur whichaccumulates at the upper end of the hearth under the feed opening I5.This low temperature fluent sulfur rapidly co-mingles with therecir-culated high ytemperature fluent sulfur and' becomes heated bycontact therewith and alsoby the heat of combustion. The ratio of hightemperature fluent sulfur is maintained large enough so that the viscousform thru which the latter passes on being heated does not deleteriouslyaffect the operation of the burner,

' This ratio is'also maintained large enough that the flow is suflicientto prevent accumulation of dirt, ash and undesirable residue upon thehearth. When feeding very dirty sulfur the ratio must obviously begreater than with clean sulfur. If an -external vsource of heat isemployed to melt the sulfur, as for example steam from a waste heatboiler in the sulfur dioxide line, some of the dirt maybe settled fromthe sulfur before it enters the burner and the ratio recirculated can bereduced. We have found a ratio of about to 1 to be satisfactory with asolid sulfur feed. However, the ratio required may vary widely withconditions.

In the modification shown in Figure 5 the partition 42 separates the lowtemperature fluent sulfur from the high temperature fluent sulfur.Y

The low temperature fluent sulfur flows down along the partition 42 andout thru the opening between the ends of this partition and the wall 1..As it continues to flow it passes thru the viscous state. This Vcausesit to dam up and fan out over the hearth 6 and thus to co-mingle withthe high temperature fluent sulfur owing down the hearth. If desired,`means may be provided for keeping the low temperature vfluent sulfurisolated Vuntil it has passed thru the viscous state so that theco-mingling with the recycled high temperature' uent sulfur takes Vplaceafter the low temperature fluent sulfur has reached the high temperaturefluent state. Such co-mingling may be Yeffected either in the hearth orin the settling pit.

If the heat content of the high temperature fluent sulfur recycled isutilized to melt the raw sulfur, as for example in the modification ofFigure '7, the recycled sulfur as well as the proportion of recycledsulfur to raw sulfur should be maintained sufficiently high in orderthat the cooling effect of melting the raw sulfur will not reduce thetemperature of the liquid to the viscous range. Thus in the modificationillustrated in Figure '7 the temperature of the recycled molten sulfurshould be maintained above about 700 F. and the ratio of recycled hightemperature fluent sulfur to raw sulfur feed should be at least about 10to 1. As in the other forms of our invention these conditions willautomatically adjust themselves in operation according to the capacityand design of the particular furnace involved.

While we have described our invention with reference to particularapparatus it will be understood that variations may be made thereinwithout departing from the spirit and scope of the invention, as set outin the appended claims, and that advantages are obtained in comparisonwith prior art sulfur burners in regard to the-ease with whichimpurities are removed from the sulfur, the considerably smaller spacerequired for-burning a given amount of sulfur, reduced formation ofsublimed sulfur throughout the system in case" of shutdowns,andfluctuations in vsulfur dioxide content by reason of incrustationsforming on the surface of molten sulfur.

We claim': v 1. Apparatusfor vaporizing sulphur comprising a chamberhaving fluid inlet Ameans and a fluid outlet passage at a lower levelthan said inlet means, Aa hearth structure therein having itsVstructureinclined to the horizontal extending in progressivelydiminishing width from a point under said inlet meansto a point at leastadjacent said outlet passage and to a width not more than approximatingthe width of said passage, an'ensaid outlet passage andto a width notmore than' approximating the width of said passage, solid-v feedingmeans communicating with the upper end of said hearth structure, anenclosed pit structure communicating with said outlet for reception offluid therefrom and fluid conduit means extending from said pit andcomprising said fluid inlet means to-sa'id chamber above said hearth.

'3. Apparatus for vaporizing sulphur comprising a chamber having fluidinlet means and a fluid outlet passage at a lower levelth'an said inletmeans,` ahearth structureI therein having vits` structure inclined tothe* horizontalextending in Y progressively diminishing widthA from a'r'point 7 under said'inlet meansvto a pointat least adjacentsaid'outletpass'age and to a width not more than approximatingthe widthof said passage, solidfeeding means communicating with the upper end fof said hearth structure, an enclosed pit structure communicating withsaid voutlet for reception of fluid therefrom, fluid conduit meansextending from said pit and comprising said fluid inlet means to saidchamber above said hearth, a variablespeed feeding mechanism' in saidsolid-feeding means, and a float in said pit in operative connectionwith said variable-speed mechanism.

4. Apparatus for vaporizing sulphur comprising a chamber having fluidinlet means and a fluid outlet passage at a lower level than said inletmeans, a hearth structure therein having its structure inclined to thehorizontal extending in progressively diminishing width from a pointunder said inlet means to a point at least adjacent said outlet passageand to a width not more than approximating the width of said passage,solidfeeding means communicating with the upper end of said hearthstructure, a combustion chamber in heat-exchange relation to saidhearth, an enclosed pit structure communicating with said outlet forreception of fluid therefrom and fluid conduit means extending from saidpit and comprising said fluid inlet means to said chamber above saidhearth.

5. Apparatus for vaporizing sulphur comprising a chamber having fluidinlet means and a fluid 7g; outietpassage aft as lower level than.said-1 inlete means?? a hearth'J structure therein having?V its:structure-ine1-inecl.to:` the-horizontal 'extending in progressivelydiminishingiwidthff-rom apoint nnder saidy inletsmeailsito-fawpoint atlleastadj acent. said'outletrpassage anditofasfwidth notfmore' thanapproximating ther Widthoffx passage, :solidfeeding means communicatingYwith the upper end of said hearth structure, a combustion-chamber?infheatxehangefrelation tosaidi hearth, an

enclosedi pits` structure; communicatingwith saidv means,en a hearth*structure therein having?. itsstructure inclined to thehorizontal;extending1 in progressively; diriiinishing:widtl'i fiom-ra:point under sai-d inletsmeafns to'af point at leastv adjacent'. saideoutlet -pas`sagefandftof ar Width*notrniorethan` approximating the'iWidth? of saidf passage, solid` v feeding? meanscommunicating witlifthe' upperA erldoff said-heath?structure;xa',-conibustiorij chamw.

ben in# heatsexcliangerelation toF said' hearth,- auf:

enclosed pit f structure communicating with said: outletY forVreceptioinofi fluidt therefrom;` fluidf con# dixitemeansV extending:froni'wsaidfpitand` compris ing--l said liuid' inletf-meanswtoisaidchamber above-y saidhear'ijlmA a5 variable-sizef` airfportin: the top--V of said pit# gas passagesl between saidpitizsaid heartlr-l containingch amben;-, and. said combustion.'

chamber, .and draft-creating. means for drawing 'v ain-throughsaidfaieperm-pit; chambersand gas passages.-

.ThApparatusv ion vapori-zingv sulphurr corriprisf-v ing achamberhavingV fluid inletl means anda fluid` outlet passage at a` lowerlevel t1'ian-sa .id7

inletV rneans, av hearth structure therein: havingVV its. strlcture,inclined-to the horizontalextending in. progressivelgy diminishing.Ywidth from a,v pointundersaid'inltmeansrto apoi`nt at leafstadjacenbsai'd'foutlt passage and-t'o awidthnotmore thanVc approximating thewidth oflsaid passage,Y solidf feeding.` rneans' corinnunicatingawiththe upper.

bei in' latlexcnang'e rennen tb. said hearth,

an` enclosed* pitfstrueture Acon;I nunieatir1gr vvitha saidoutlet-fforreception Y015fluid#.tiierefrom.ilnid. Y conduit means extendingiromsaid pit-and com-fi prising. said fluid inlet -f meansr to said:chamber. above saidt hearth-,. a..-var-iabllff-5mied feeding mechanisminsaidssolid-eedingmeans, ailoa.t inv said' piti infoper-ativeconnection withs-said-x variable-s1f eedAv :mechanism a variable-sizeair: portin the topoff said pit;gasrpassagefbetween saithV pit,- saidhearthcontaining;I chamber, andsaid combustion'- chamber; andfdrain-creating; means for drawing ainthroughisaidairrpert; pit;`chamberssand gas:passages; 1 f 8.1Apparatus-fore vaporizingasulphurcomprisingVV ai chamber having uidinlet'V means and#Y a fluid` outletpassage; at ai lower.1 levelf than'said inlet nieans;v a r hearth:structure therein'4 having its stuctnrezinclined torthef horizontal?extending: in; progressively diminishing Widthi from Iafpoint. un-

. der saidsinlet means toffa point-y atleastradiacentsaidioutleizpassage anditofa Width not more-thanapproximating1thefvvidth:of'saidv passage, awcome f bnstionr chambenin"- heat-exchangerelationtoe said i hearth, anf enclosed pitistructurer corrimunif'A -cating With said: otletyfoii reception: of: Yiluidr:

